SQL数据库按照 小时， 月，年排序

按小时排序：datepart(hour,d_time)

     select datepart(hour,d_time)  as  dtime,n_amount 
     from 表
    where n_server_id=XX
     and d_time>='2012-09-13'
     group by datepart(hour,d_time),n_amount

按照分钟排序：20分钟一次的

select   convert(varchar(10),d_time,120) as '日期',datepart(hour,d_time)  as  '小时',n_amount  as '记录'
from GAME_ONLINE_STAT 
where n_server_id=71
and d_time>='2012-09-13'+' 00:00:00'
and d_time<'2012-09-14'+' 23:59:59'
group by convert(varchar(10),d_time,120),datepart(hour,d_time),datepart(mi,d_time)/20,n_amount
order by datepart(hour,d_time)